CHAPEL HILL, N.C. (AP) — A long-running parking dispute between neighbors motivated a man to kill a woman, her newlywed husband and her sister at a quiet condominium complex near the University of North Carolina campus, police said Wednesday.

Beyond the parking arguments, police didn't comment further on the motivation or details of the crime, but a Muslim civil rights and advocacy organization asked authorities to address speculation — much of it on social media — about possible religious bias.

Barakat and Mohammad were married, and Abu-Salha was Mohammad's sister.

Hicks appeared briefly in court Wednesday. He spoke only to answer that he understood the charges and to confirm an indigency affidavit. District Judge Marcia Morey said he would be appointed a public defender and held without bond. She scheduled a probable cause hearing for March 4.

Police said Hicks was cooperating and that their preliminary investigation showed that the parking dispute was the motive.

But outrage spread among American Muslims who viewed the homicides as an outgrowth of anti-Muslim opinions in the U.S. Many posted social media updates with the Twitter hashtags #MuslimLivesMatter and #CallItTerrorism.

"Based on the brutal nature of this crime ... the religious attire of two of the victims, and the rising anti-Muslim rhetoric in American society, we urge state and federal law enforcement authorities to quickly address speculation of a possible bias motive in this case," Nihad Awad, of the Council on American-Islamic Relations, said in a statement.

In an email, Chapel Hill police Chief Chris Blue said, "We understand the concerns about the possibility that this was hate-motivated, and we will exhaust every lead to determine if that is the case."

Durham district attorney Roger Echols said he couldn't discuss a motive. Asked whether Hicks could be charged with a hate crime, he said the facts of the case were still under investigation.

A spokeswoman for the U.S. attorney's office in North Carolina that encompasses Chapel Hill didn't immediately return messages seeking comment about whether federal prosecutors were involved or looking into a possible hate crime.

Abdullah Antepli, director of Muslim affairs at nearby Duke University, issued a statement calling for people not to jump to conclusions over the motive for the killings.

At UNC, Barakat was a second-year dental student, and Yusor was scheduled to begin dental studies in the fall.

Both had graduated from North Carolina State University, school spokesman Mick Kulikowski said. Barakat graduated with a business administration degree in the spring of 2013. Mohammad graduated in December with a biological sciences degree.

Abu-Salha was a sophomore design major who had started classes last fall, Kulikowski said.

Muneeb Mustafa, 23, of Cary, attended the same Raleigh mosque as Barakat.

"He was a completely genuine guy. Loving, caring, friendly, smart," Mustafa said. "He was an ideal human being. He was a role model."

Mustafa said they last saw each other about a month ago, playing in a basketball tournament staged by the Muslim Student Association at UNC, Mustafa said. Barakat, his wife of less than two months and his sister were all Muslim, Mustafa said.

Barakat's family was from Syria, and he was raising money to help refugees of the country's civil war, Mustafa said. Mohammad traveled to Turkey last summer to help treat dental problems in Syrian refugees in that country, Mustafa said.

The neighborhood where the victims were found — about three miles east of campus — consists mostly of apartments and condominiums rented by students. Residents said they'd never before seen police or had crime problems there.

"It's a very quiet community," resident Bethany Boring told WRAL-TV. "It's a lot of graduate and professional students. You know, professional families."

Police tape hung near the apartment where the victims were found, but otherwise there was no indication of a crime scene. Outside the victims' apartment, a woman's bicycle with a helmet was parked by the stairs.

Shadi Wehbe, a UNC graduate who has lived in the complex since 1999, said that two weeks ago, a woman came to his door about 10 p.m. to ask him to move his car. Some of the parking spots are assigned, and others are open. Wehbe said parking had never been a problem and no one had asked him to move his car before, but he realized he was in the wrong spot and moved his car one place over.

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Associated Press writers Jonathan Drew in Durham, Emery Dalesio in Raleigh and Eric Tucker in Washington contributed to this report.

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